As solutions for intraocular or extraocular irrigation or cleaning in ophthalmic surgeries such as cataract surgery, vitreous surgery and glaucoma surgery, “Opeguard” (produced by Senju Pharmaceutical Co., Ltd. and sold by Takeda Chemical Industries, Ltd.) and BSS PLUS (imported and sold by Santen Pharmaceutical Co., Ltd.) are commercially available at present.
The former “Opeguard” is in liquid form within a pH range of 7.2–8.2 and comprises dextrose as an active ingredient. This product has a disadvantage of lacking long-term storage stability because dextrose is stable in an acid pH environment.
The latter “BSS PLUS” is in such a form that a solution (10 ml or 20 ml) containing oxiglutatione, dextrose, calcium ion and magnesium ion and a diluent (240 ml or 480 ml) containing bicarbonate ion are separately stored in glass vials, the solution containing oxiglutatione, etc. being transferred into the vial containing the diluent using a syringe having a double ended needle and mixed together before use. This is because it is difficult to stably maintain oxiglutatione and dextrose at pH 7 or above for a long time and because there is a disadvantage that calcium ion and magnesium ion in contact with the diluent for a long period of time cause precipitation.
The above “BSS Plus” can be stably stored for a long period of time but requires transferring procedures as shown below in (1) to (4) and consequently has the disadvantages as shown below in (a) to (f).    (1) A cap is removed from the rubber stopper of the glass bottle containing 10 ml or 20 ml of the oxiglutatione solution, and a cap is removed from the resin needle at one end of the syringe. The rubber stopper of the bottle is pierced by the needle.    (2) Next, a cap is removed from the stainless steel needle at the other end.    (3) An aluminum cover is removed from the glass bottle containing the diluent, and the rubber stopper of the bottle is pierced by the stainless steel needle.    (4) After transferring the oxiglutatione solution into the bottle of the diluent, the two liquids are well mixed.    (a) The above procedure itself is complicated. Especially, the operation of piercing the rubber stopper of the oxiglutatione solution-containing bottle with the resin needle is considerably difficult.    (b) The transferring and mixing of the two liquids take too much time to be responsive to urgent use.    (c) The risk of bacterial contamination at the time of transferring and mixing can not be avoided.    (d) The risk of foreign matter contamination increases if the resin needle is stuck into the rubber stopper of the bottle twice or more.    (e) If the mixing procedure is mistaken, the two liquids are not mixed or the concentration of the resulting solution changes.    (f) There is a possibility that only the diluent is inadvertently administered without mixing with the oxiglutatione solution.
Moreover, not only “Opeguard” and “BSS Plus” but also these types of ocular irrigating solutions are generally in the liquid form, stored in glass vials and adjusted to an alkaline pH range near pH 8 using bicarbonate ion. Therefore, if placed in glass bottles and then sterilized by heating for preservation, the conventional products have a fatal defect that the glass falls in flakes with the lapse of time.
Therefore, there is desired in this industry the development of a new ocular irrigating solution which replaces conventional ocular irrigating solutions and solves all the defects of the conventional solutions.
Bicarbonate ion (hydrogencarbonate ion) used in these types of ocular irrigating solutions is at equilibrium in solution, as represented by the following formula (1):
In an open system, the reaction proceeds to the right as the carbon dioxide gas on the right-hand side of formula (1) evaporates, with the result that the bicarbonate ion decreases and the carbonate ion increases. As a result, the pH of the aqueous solution rises progressively.
Healthy human lacrimal fluids are within a pH range of 7.5±0.2 in the arousal state, and at about pH7.25 in the condition that the eyes are closed for hours. It is necessary to adjust the pH of an ocular irrigating solution to the above-mentioned range as much as possible because the human feels discomfort when it is out of the above pH range, for example, at pH6 or below or at pH8 or above. The pH rise deviating from this range must be prevented to the utmost.
Therefore, in order to prevent the time-dependent pH change, ocular irrigating solutions are conventionally contained in glass vials or like sealed containers for preventing evaporation of evolved carbon dioxide gas to thereby maintain the equilibrium essential to the stabilization of bicarbonate ion concentration and solution pH.
However, containers made of glass are easy to be broken, are very heavy and involve difficulties in disposal. In addition to these fatal defects, since the evolution of carbon dioxide gas in the course of sterilization of the ocular irrigating solutions is unavoidable, the risk for an elevation of internal pressure inducing fracture of the glass container is high.
Further, there is another disadvantage. As stated above, it is preferable for bicarbonate ion-containing ocular irrigating solutions to be weak alkaline solutions within a pH range of about 7–8. At such pH, however, if the solutions are placed in glass containers and sterilized by heating for preservation, the glass of the container wall falls in flakes with the lapse of time, making long-term preservation impossible.
An object of the present invention is to overcome all the above-mentioned defects of the prior art and provide a packaged ocular irrigating solution bag which is capable of providing an oxiglutatione- and/or dextrose- and bicarbonate ion-containing ocular irrigating solution in stable condition for a long period of time, most effectively preventing the pH change of the bicarbonate ion-containing solution due to evolution of carbon dioxide gas and providing an unmistakable visual indication of the pH change of the solution.
The present inventors carried out intensive research to achieve the above object and found the following. In a gas-permeable plastic multiple compartment bag, a bicarbonate ion-containing solution is enclosed in one of the compartments and an oxiglutatione- and/or dextrose-containing solution or solid preparation is enclosed in another compartment, followed by sterilization thereof according to a general sterilization method such as autoclave sterilization, hot water immersion sterilization or hot water shower sterilization, or the above pharmaceuticals are aseptically enclosed in the compartments. Then the obtained bag is packed with a gas-impermeable plastic packaging member, and carbon dioxide gas is fed into the space between the bag and the packaging member. In such a case, an ocular irrigating solution can be prepared by bringing the compartments of the bag into communication with each other and mixing the contents of the bag when used, thus enabling stable storage of the ocular irrigating solution, which is one of the objects of the invention.
The present inventor further found that when the multiple compartment plastic bag is packed with a gas-impermeable plastic packaging member and a specific pH indicating device is disposed in the space between the bag and the packaging member, pH change of the bicarbonate ion-containing solution in one of the compartments of the bag can be accurately checked with the eye. The present invention has been accomplished based on these findings.